2012/3/22 Martin K. Petersen <martin.petersen@xxxxxxxxxx>: >>>>>> "Shaohua" == Shaohua Li <shli@xxxxxxxxxx> writes: > > Shaohua> Enabling discard merge is required for device with slow discard > Shaohua> (and very helpful for raid), > > Before RAID support there really wasn't much point. That's one of the > reasons the current discard merge code has survived despite being > completely broken. Exactly. > As for how I'd like to handle contiguous discard merges going forward > here's a proof of concept. It's on top of my write same tree so you may > have to noodle a bit. > > It is crucially important that we never merge a command that can't be > processed by the device. So I'd like to do something like this: This is great to consolidate the check with this patch. But looks this isn't enough. As far as I know the current discard merge is broken because blk_update_request() can't handle such request because we override the first BIO to add payload. I had a quick hack and post out yesterday. It works in my SATA ssd, but I really didn't know if there is something missing in SCSI side, can you share anything here? Thanks, Shaohua -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
